Ccna routing and Switching Complete Study Guide

WAN Topology Options

A physical topology describes the physical layout of the network, in contrast to logical 

topologies, which describe the path a signal takes through the physical topology. There are 

three basic topologies for a WAN design.

Star or hub-and-spoke topology    This topology features a single hub (central router) 

that provides access from remote networks to a core router. Figure 21.1 illustrates a 

hub-and-spoke topology:

f i g u r e   21.1    Hub-and-spoke

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Chapter 21 

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  Wide Area Networks

All communication among the networks travels through the core router. The advantages of 

a star physical topology are less cost and easier administration, but the disadvantages can 

be significant:

 

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The central router (hub) represents a single point of failure.

 

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The central router limits the overall performance for access to centralized resources. It 

is a single pipe that manages all traffic intended either for the centralized resources or 

for the other regional routers.